1. Field of the Invention
The present invention relates to an improved high voltage device, and more particularly, relates to the construction of a high burst strength one piece enclosure for a high-voltage device. The enclosure is formed from a flexible material reinforced with glass fiber, so that when the device operates, high pressure generated by the device causes the flexible material to give, thereby loading the glass fiber in tension.
2. Description of the Prior Art
The construction of high-voltage devices, such as fuses and fault limiters, including current-limiting fuses, is difficult and often expensive because internal forces which are generated during operation of the devices require a sturdy, well-constructed fault limiter enclosure. Furthermore, such devices are often mounted outdoors, where they are subjected to rough handling, the elements, and other adverse conditions such as pollution. Therefore, special care must be taken to ensure that the enclosures of such fault limiters are rugged and resistant to surface leakage currents.
The prior art discloses the use of rigid, multiple piece, resin enclosures for current limiting fuses wherein the space between a fusible element and the rigid enclosure is filled with a particulate arc-quenching medium. For example, such enclosures are shown in U.S. Pat. No. 4,035,753--Reeder, and pending U.S. patent application Ser. No. 817,985--Biller, filed July 22, 1977 as a continuation of Ser. No. 708,146, filed July 23, 1976 and now abandoned, both assigned to the same assignee as the present invention. The prior art also discloses the use of multiple-piece rigid glass-reinforced resin enclosures as shown in U.S. Pat. Nos. 3,983,525--Healey; 3,986,157--Salzer; and 3,986,158--Salzer. These prior art devices do not utilize one-piece enclosures, and therefore their structural integrity may be compromised, since separate end caps must usually be attached to the enclosure after it is filled with the arc-quenching material. A one-piece housing can be achieved utilizing the invention described in copending application Ser. No. 8,424 filed Feb. 1, 1979 in the name of Guleserian, and assigned to the same assignee as the present invention; however, the Guleserian device is not glass reinforced, and therefore is not as strong as the present invention.
When the present invention is used with a current-limiting fuse, the foregoing disadvantages are overcome because the arc-quenching material may be positioned around the fusible element within a subassembly prior to molding a one-piece glass-reinforced flexible enclosure around the subassembly. Accordingly, the present invention provides a desirable advance in the art by providing a highvoltage current-limiting fuse construction which permits relatively simple, inexpensive manufacturing techniques, while preserving the requisite strength and leakproof characteristics necessary for proper operation.